The production of active carbon from brown coal in high yields

The acid-leached char produced in high yield by the pyrolysis of the potassium salt of a brown coal (Yallourn seam, Victoria, Australia) is shown to have an internal surface area in excess of $\text{1100}\text{m}{}^2\text{g}$ without the need for activation. Tabletting, or extrusion, of the potassium salt of the coal permits production of a hard, active carbon as shaped granules. Of the cations investigated — sodium, potassium and magnesium — potassium was unique with regard to the formation of such a highly active char.